Method for production of materials having anisotropic properties composed of nanofibres or microfibres and an apparatus for implementation of said method

ABSTRACT

A method of producing fibres includes continuously drawing a fibre out of a solution, and pulling it to a rotary set of n electrodes by means of an electrostatic field. The individual electrodes of the set are arranged at regular spacing to each other and at the same distance from the set&#39;s rotation axis, and parallel with it. The fibre is wound on the set of electrodes by rotating the set of electrodes. The electrostatic field is disconnected and rotation of the set of electrodes is stopped. A layer of the fibres formed in the field between two adjacent electrodes is removed. The rotating set of electrodes turns through an angle of 360/n, the layer of the fibres formed between two adjacent electrodes in the field adjacent to the field from which the layer was removed, is removed, and this step is repeated in total n-times.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for production oftwo-dimensional or three-dimensional fibrous materials of microfibres ornanofibres in which at first nanofiber or microfiber is continuouslydrawn out of a solution, which nanofibre or microfibre is pulled to arotary set of n electrodes by means of electrostatic field. In theprocess individual electrodes are arranged at regular spacing to eachother and at the same distance from the set of electrodes rotation axisand parallel with it. This set of electrodes rotates and thereby thenanofibre or microfibre is wound on it. After the nanofibre ormicrofibre was wound the electrostatic field is disconnected androtation of the electrode set is stopped, and a layer of microfibres ornanofibres formed in the field between two adjacent electrodes isremoved. The invention also refers to an apparatus for production of thetwo-dimensional or three-dimensional fibrous materials of microfibres ornanofibres. This apparatus includes at least one spinning nozzleattached to a first potential and a set of electrodes facing the nozzlearranged at regular spacing to each other and attached to a secondpotential. Further it includes an accumulator for collecting microfibresand nanofibres settled between couples of adjacent electrodes.

BACKGROUND OF THE INVENTION

Production of microfibres or nanofibres is implemented by a method ofelectrostatic spinning. This method is presented as “Electrospinning” inprofessional literature. In this method the forming of melt or solutionof polymers into fibrous structures is brought about by effects of highelectrostatic field. Forces of this field at first give rise to a spurtof a trickle out of the polymer solution or melt droplet and then theyactivate also its movement to an opposite electrode. During the movementa thinning, drawing and solidification of the polymer occur and thepolymer in the solid fibres form falls on the opposite electrode,so-called collector. The whole of this fibre movement between the twoelectrodes is highly complicated and its trajectory is quite random.Literally chaotic movement of the flying fibre gives rise to its randomdepositing on the opposite electrode, where a nonwoven fibrous materialwith fibres having their diameter from ten nanometres to tens ofmicrometres is formed. This manufacturing method is known from U.S. Pat.No. 2,048,651.

Nano-fibrous or micro-fibrous materials with highly fine structure findnumerous applications in many fields of advanced medicine, but also ofmicroelectronics, optics and power engineering. Huge surface formed inrelatively very small volume is one of the basic advantages of thesematerials, and inter-fibre spaces (pores) of these materials have verysmall size. Material with fine internal nano-structure ormicro-structure assumes quite new properties that can be considerablydifferent from properties of a volume sample of the same material.Additionally it is possible to control these unique properties and adaptthem to requirements of particular application by a controlledproduction. Future applications count on a use of such materials invarious fields of advanced medicine, because such material providescells in living tissue with very favourable and natural conditions fortheir growth, motion and reproduction. Unfortunately the usability ofsuch material is considerably limited just because of its internalchaotic structure. Applications of tissue engineering specify theirrequirements on regular 3D structures that are subsequently used asreplacements of cartilages, bones, and nerve, vascular andcardiovascular transplants and the like. Just an internal axialorderliness of material considerably supports directional growth andmotion of cells, tissues, and also supports regeneration of long nervousdisorder. The ordered structure ensures required flexibility of thematerial when stressed in applications such as muscular and connectivetissues replacements. Mechanical properties of the material can be quitewell controlled just by choice of the internal structure axialorderliness. Need of new materials with precise internal morphology isrequired by numerous applications not only in the field of advancedmedicine. The regular structure is quite essential also e.g. forminiature electronic or optical connections that can be provided bynanofibres or microfibres produced by the method disclosed in thisinvention.

Current methods and production techniques of the oriented nanofibres ormicrofibres are solved by means of rotating collector that is driven athigh revolutions. Surface of such collector, in most cases in the shapeof a cylinder or a thin rod as described in U.S. Pat. No. 4,552,707 orU.S. 20020084178, captures flying fibre and mechanically carries it inthe direction of the collector own movement; the fibre is practicallywrapped around the rotating cylinder. Nanofibres or microfibres aredeposited directly onto the cylinder surface or are formed in a gapbetween two rotary rods that are positioned on one rotation axis, seeU.S. 20070269481. Surface of such collector is one of the electrodes andthus it must be made of a conductive material. Unless the collector isdirectly connected to one of high-voltage power supply poles, see U.S.20090108503, U.S. Pat. No. 4,689,186, or if its surface is overlappedwith non-conductive substrate, significant losses of the productionprocess efficiency arise, because practically an insulating material isinserted between two main electrodes and thus electric field is degradedand its homogeneity is disturbed. Reduced efficiency is indicated withlonger deposition of fibres, because the thicker deposited layer actsalso as an undesirable insulant and thus further fibres are repelled ina different direction from the collector. In the area of so fardeposited fibres a charge is accumulated that has the same polarity as acharge carried by a fibre before its impact on the collector. Repulsiveforces act between these charges of the same polarity, which forcesinfluence negatively the ordering of newly deposited fibres. Thenegative effects of this charge are increased, when thicker fibrouslayers are deposited, because fibres in upper layers are alreadydeposited randomly and no longer respect the axial orderliness as it iswith fibres deposited in lower layers. Furthermore the resulted fibrouslayer has a partially limited degree of order, which is caused bycapturing the flying fibre having direction different from justperpendicular to the surface of the rotating cylinder. On principal themethods mentioned above function well, however results, with regard toachieving precise orientation of the internal structure of the fibrousmaterials, are generally unsatisfying, because there is still highpercentage of fibres in produced materials that do not respect any ofpreferred directions.

Subsequent manipulation with the fibrous material and its controlledtaking off from the collector surface is quite essential problem that isnot a part of any of contemporary technical solutions. The fibrous layeris deposited onto the collector and for its subsequent use it must betransferred usually onto quite different underlayment or into anothercontainer, etc. And so manually one by one cut out stripes of fibrousmaterial are assembled in thicker 3D structures in examples ofembodiments disclosed in patent application U.S. 20080208358A1. Such alayer is highly fine and a manipulation with the nano-fibrous ormicro-fibrous material is complicated, because an irreversible damage ofthe layer arises very easily already when being taken off from thecollector used. Any manipulation with material of a larger area isalmost impossible especially with bio polymeric fibres with very lowmechanical resistance. Currently there is no mechanisms solved, whichwould provide suitable mechanical manipulation and transfer ofnano-fibrous or micro-fibrous layer onto another,, i.e. any underlaymentwhile maintaining or even increasing of the orientation degree of thefibres in the layer.

Patent application WO2006136817A1 describes a use of a rotatingcollector with electrodes longitudinally arranged around an axis ofrotation. Geometric dimensions of the collector are not mentioned.Authors give no method for taking off fibres from the collectorcarefully. No collecting mechanism for fibres deposited onto therotating collector is solved. The described method does not solve allphases of the production process or more precisely the process isterminated by the fibres deposition. Therefore it is impossible tofinish the production process without an operator intervention andmanual manipulation, which results in considerable decreasing of qualityand internal structure of the material.

In publication of Katta et al. (Katta P., M. Alessandro et al.NanoLetters, 4(11): 2215-2218, 2004) rotating cylinder built-up oflongitudinal conductive electrodes as a collector for creating orientedfibres is used. The collector with approximately forty conductiveelectrodes, which are distant 10 mm from each other and create therotating collector with diameter of 120 mm, is described in thepublication. A loss of uniaxial fibres orientation during longer timedeposition is demonstrated here. Optimization and description ofparameters important for operational utilization are not carried outhere. The authors also do not mention further steps for processing ofthe fibrous layer deposited onto this type of collector.

SUMMARY OF THE INVENTION

Drawbacks of state of the art mentioned above are eliminated to aconsiderable extent by a method of production of two-dimensional orthree-dimensional fibrous materials of fibres with a diameter ofmicrofibres or nanofibres according to the invention, in which at firstnanofibre or microfibre is continuously drawn out of a solution, whichnanofibre or microfibre is pulled to a rotary set of n electrodes (wheren is a natural number from 1 to 200) by means of an electrostatic field.Individual electrodes of the set are arranged at regular spacing to eachother and at the same distance from the set of electrodes rotation axisand parallel with it. This set of electrodes rotates and thereby thenanofibre or microfibre is wound on it. After the nanofibre ormicrofibre thin layer was formed the electrostatic field is disconnectedand rotation of the electrode set is stopped, and a layer of microfibresor nanofibres formed in the field between two adjacent electrodes isremoved. Afterwards the rotary set of electrodes turns through an angleof 360/n and the layer of microfibres or nanofibres formed between twoadjacent electrodes in the field adjacent to the field, from which alayer was removed in previous step, is removed. This step is repeatedn-times till layers of microfibres or nanofibres from all the fieldsbetween adjacent electrodes are removed.

In an advantageous embodiment of the method according to the invention,before the layer of microfibres or nanofibres is removed from a newfield, an accumulator turns around slightly to reach a direction ofmicrofibres or nanofibres in the removed layer that is different fromthe direction of microfibres or nanofibres of the preceding layer.

In another advantageous embodiment of the method according to theinvention superimposed layers of microfibres or nanofibres are pressedtogether, whereas by pressing the layers together it is possiblesimultaneously to form a required three-dimensional shape of the finalproduct. An article formed in this way can be embedded with anothermedium to create a composite material of required properties.

Drawbacks of the state of the art mentioned above are eliminated to aconsiderable extent even by an apparatus for production oftwo-dimensional or three-dimensional fibrous materials of microfibres ornanofibres comprising at least one spinning nozzle connected to a firstpotential and a set of n electrodes facing the spinning nozzle that arearranged at regular spacing and connected to a second potential, andalso an accumulator for collecting microfibres or nanofibres settledbetween two adjacent electrodes. The set of the electrodes is pivoted inthis apparatus and individual electrodes of the set of the electrodesare arranged at regular spacing to each other and at the same distancefrom the set of electrodes rotation axis and parallel with it. Theapparatus further comprises the accumulator, which is arranged, inrelation to the electrodes, movably in direction of longitudinal axes ofthe electrodes, for collecting microfibres or nanofibres settled betweentwo adjacent electrodes. Furthermore this accumulator is arranged, inrelation to the electrodes, movably in direction perpendicular to thelongitudinal axes of the electrodes for it being brought into engagementto collect microfibres or nanofibres settled between two adjacentelectrodes, and being brought out of engagement after finishing thecollection of microfibres or nano fibres settled between two adjacentelectrodes.

In an advantageous embodiment of the apparatus according to theinvention the accumulator has a shape of parallelogram, the width ofwhich is smaller than a distance between nearest surfaces of a couple ofadjacent electrodes to enable its insertion between said adjacentelectrodes.

In another advantageous embodiment of the apparatus according to theinvention the accumulator is arranged rotationally around a lineperpendicular to the surface of the collector and passing through thecentre of the collector surface in order that the accumulator may turnaround slightly to place a further layer of microfibres or nanofibressettled between two adjacent electrodes with direction of microfibres ornanofibres that is different from the direction of microfibres ornanofibres of the preceding layer.

In another advantageous embodiment of the apparatus according to theinvention the accumulator has a shape of square with its side shorterthan a distance between nearest surfaces of a couple of adjacentelectrodes, the accumulator being arranged rotationally around a lineperpendicular to the surface of the collector and passing through thecentre of the collector surface in order that the accumulator may turnthrough an angle of 90° to place a further layer of microfibres ornanofibres settled between two adjacent electrodes with direction ofmicrofibres or nanofibres that is perpendicular to the direction ofmicrofibres or nanofibres of the preceding layer.

In yet another advantageous embodiment of the apparatus according to theinvention the accumulator is made in the form of a dish for depositingthe collected layers of nanofibres or microfibres, the apparatus beingfurther provided with a piston for compression of the fibres into theaccumulator and for compaction of individual collected layers ofnanofibres or microfibres to mechanically strengthen ordered 3Dstructure. In such a case it is also advantageous if the accumulator isarranged rotationally around a line perpendicular to the surface of thecollector and passing through the centre of the collector surface inorder that the accumulator may turn around slightly to place a furtherlayer of microfibres or nanofibres settled between two adjacentelectrodes with direction of microfibres or nanofibres that is differentfrom the direction of microfibres or nanofibres of the preceding layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is described in details withreference to the accompanying drawings. FIG. 1 is a flow chart ofparticular phases of the production process as suggested in solutionaccording to the present invention. FIG. 2 represents an exemplaryembodiment of an apparatus for the production of fibrous materials withanisotropic properties. Side sectional elevation of longitudinalelectrodes of a rotating collector with accumulator is on FIG. 3, andfurther exemplary embodiment is on FIG. 4 a. FIG. 4 b shows a crosssection of four and five longitudinal electrodes of a rotatingcollector, whereas principal of parallel ordered fibres formation isdepicted. In a similar way principal of the production of perpendicularfibres in two steps with exemplary use of four and five longitudinalelectrodes of the rotating collector is shown on FIGS. 5 a and 5 b.Photos of parallel and perpendicular ordered fibres from an electronmicroscope are on FIGS. 6 and 7.

DETAILED DESCRIPTION OF THE INVENTION

It is the aim of the present invention to accomplish the production ofnano-fibrous or micro-fibrous materials with high degree of areal (2D)and volume (3D) internal ordering that can be controlled by changingprocess parameters for the purpose of controlling morphological andanisotropic properties of the resulting materials. Furthermore it isalso the aim of the present invention to solve suitable mechanicalmanipulation and transfer of the new material onto any underlying oralso packing material, whereas the order degree of internal structure ofthe material is maintained. In an advantageous embodiment of theinvention a movable accumulator 7 is a suitable dish that enables easyfurther treatment of the fibrous material (e.g. in production ofcomposite materials).

The subject matter of the invention is a comprehensive productionprocess of new materials that is divided into particular process phases,the exemplary sequence of which is shown on FIG. 1. A spinning mixtureis prepared in the first step. Subsequently the solution or melt 1 ismeasured out into a spinning nozzle 3, after which a high electricvoltage is connected, which gives rise to a fibre 5 with a diameterranged from microfibres to nanofibres. The fibre 5 moves in theelectrostatic field in the direction to a collector 9. Fibres 5 aredeposited onto the rotating collector 9 in one preferred direction.After a layer 8 of fibres 5 was created on the collector, the depositedfibres 5 are collected and layers 8 of these fibres 5 are in turnsuperimposed, while the degree of their order is maintained. Thereafterthe fibre layers 8 are compressed, through which a finished product thatcan be enfolded in a wrapping material, or a semi product intended forfurther processing such as an application of suitable medium so that theresulted product may be a composite material and gain requiredproperties, comes into existence. It is possible to enfold the finishedproduct in the wrapping material with the shape of a tray that makesmanipulation easier and is also suitable for subsequent treatments offibre layers 8 such as embedding the layer 8 of fibres 5 with anothermedium in order to get a composite material, and thus a final productcomes into existence. Removing and transfer of the product is a finalphase. Advantageously all of these phases are implemented automaticallyin a deposition chamber without any intervention of an operator andwithout being affected by external environment, which makes it possibleto ensure the process sterility and a high quality of final products.The production process phases are represented in the flow chart on FIG.1, where repeated process phases are also indicated. The process isrepeated from the beginning unless a sufficient layer 8 of fibres 5 iscollected by the accumulator 7 at the moment of solution 1 reserveexhaustion in phases “Fibres deposition” or “Superimposing”.

An exemplary embodiment of an apparatus for production oftwo-dimensional or three-dimensional fibrous materials composed ofnanofibres or microfibres, hereinafter referred to as fibres 5, is onFIG. 2. This apparatus comprises a jet emitter 2 filled with solution 1of polymer and equipped with spinning nozzle 3. In spite of the factthat for simplicity's sake only one jet emitter 2 is depicted on FIG. 2,it is obvious that there will be more such jet emitters 2 in actualapparatus. The spinning nozzle 3 is connected to a first potential, i.e.to one of poles of a source 4 of DC electric voltage. The second pole ofthe source 4 of DC electric voltage is connected to the collector 9facing the spinning nozzle 3. The collector 9 is composed of electrodes6 that are arranged longitudinally at regular spacing to each other andat the same distance from the collector 9 rotation axis x. Theaccumulator 7 is arranged movably, in relation to the electrodes 6, indirection parallel with the rotation axis x of the collector 9 so thatthe accumulator 7 may collect layers 8 of fibres 5 settled between twoadjacent electrodes 6.

FIG. 3 schematically depicts a side view of an accumulating mechanismwith the planar accumulator 7. Fibres 5 are deposited by electrostaticspinning onto the electrodes 6 of the collector 9. Afterwards the fibres5 are deposited onto a surface of the accumulator 7 while their order ismaintained. In this exemplary embodiment the accumulator 7 is planar. Itis inclined in relation to the rods of the electrodes 6 of the collector9 at an angle α, and moves in translatory movement in the direction thatforms an angle β with the axis x of the collector.

FIG. 4 a schematically depicts a cross-section of the collector 9 withfour electrodes 6 and the accumulator 7. Fibres 5 are deposited byelectrostatic spinning on the conductive rods of the electrodes 6 of thecollector 9. Afterwards the fibres 5 are deposited on a surface of theaccumulator 7 while their order is maintained. The collector 9 isequipped with four electrodes 6. The squared accumulator 7 removed alayer 8 of fibres 5 from the field between two upper electrodes. On theright the subsequent phase is depicted, where the collector 9 is turnedthrough an angle of 90° and the accumulator removes another layer 8 offibres 5 with the same orientation.

FIG. 4 b schematically depicts a cross-section of the collector 9 withfive electrodes 6 and the accumulator 7. Fibres 5 are deposited byelectrostatic spinning onto the conductive rods of the electrodes 6 ofthe collector 9. Afterwards the fibres 5 are deposited on a surface ofthe accumulator 7 while their order is maintained. The collector 9 isequipped here with five electrodes 6. The squared accumulator 7 removeda layer 8 of fibres 5 from the field between the two upper electrodes.On the right the subsequent phase is depicted, where the collector 9 isturned through an angle of 360/5, i.e. 72° and the accumulator 7 removesanother layer 8 of fibres 5 with the same orientation. There are twolayers 8 of fibres 5 with the same orientation on the accumulator 7.

FIG. 5 a schematically depicts a cross-section of the collector 9 withfour electrodes 6 and the accumulator 7. Fibres 5 are deposited byelectrostatic spinning on the conductive rods of the electrodes 6 of thecollector 9. Afterwards the fibres 5 are deposited on the surface of theaccumulator 7, while their order is maintained. The collector 9 isequipped with four electrodes 6. The squared accumulator 7 removed alayer 8 of fibres 5 from the field between the two upper electrodes. Onthe right the subsequent phase is depicted, where both the collector 9and the accumulator 7 are turned through an angle of 90° and theaccumulator 7 removed another layer 8 of fibres 5. Thus there are twolayers 8 of fibres 5 on the accumulator 7, whereas the orientation offibres 5 of the first layer 8 is perpendicular to the orientation offibres 5 of the second layer 8.

FIG. 5 b schematically depicts a cross-section of the collector 9 withfive electrodes 6 and the accumulator 7. Fibres 5 are deposited byelectrostatic spinning onto the conductive rods of the electrodes 6 ofthe collector 9. Afterwards the fibres 5 are deposited on the surface ofthe accumulator 7, while their order is maintained. The collector 9 isequipped here with five electrodes 6. The squared accumulator 7 removeda layer 8 of fibres 5 from the field between the two upper electrodes.On the right the subsequent phase is depicted, where the collector 9 isturned through an angle of 360/5, i.e. 72°, and the accumulator 7 isturned through an angle of 90° and removes another layer 8 of fibres 5.Thus there are two layers 8 of fibres 5 on the accumulator 7, whereasthe orientation of fibres 5 of the first layer 8 is perpendicular to theorientation of fibres 5 of the second layer 8.

FIG. 6 is a photo from an electron microscope at magnification5000-times, where several layers 8 of fibres 5 superimposed with thesame orientation are depicted.

FIG. 7 is a photo from an electron microscope at magnification1000-times, where several layers 8 of fibres 5 are depicted, whereaslayers 8 were superimposed in such a way that the orientation of fibres5 of one layer 8 is perpendicular to the orientation of fibres 5 of theprevious layer 8.

In operation of the apparatus for production of the two-dimensional orthree-dimensional fibrous materials a prepared spinning mixture is dosedinto the jet emitter 2. Afterwards a high electric voltage is connectedand it causes that the solution or melt begins to escape out of thespinning nozzle 3 creating fibre 5 with diameter ranging frommicrofibres to nanofibres. This fibre 5 moves in the electrostatic fieldin the direction to the collector 9. The fibres 5 are deposited onto therotating collector 9 in one preferred direction. After the layer 8 ofthe fibres 5 was formed on the collector 9, high electric voltage isdisconnected and the fibre 5 quits escaping out of the spinning nozzle3. Thereafter the accumulator 7 collects the settled fibres 5, and thelayers 8 of these fibres 5 are step by step superimposed, while theirdegree of order is maintained. According to requirements on the resultedmaterial, the layers 8 of the fibres 5 are superimposed so that thefibres 5 orientation may be the same in all layers, or it is possible toturn the orientation of the fibres 5 in each subsequent layer 8 throughan angle, usually through 90°. After a sufficient number of the layers 8was superimposed it is possible to compress the fibrous layers 8 andthus either a final product, that can be enfolded in a wrappingmaterial, or a semi product intended for further processing such as anapplication of suitable medium so that the resulted product may be acomposite material and gain required properties, comes into existence.

It is an advantage of this embodiment that the fibres 5 deposited ontothe surface of the accumulator 7 have a higher degree of order thanfibres 5 settled onto a surface of a rotating cylinder because furtherstraightening of them in one direction occurs just by a movement of theaccumulator 7. Thus the degree of order of the internal fibrous materialstructure is higher than that of the material that was formed on thesurface of the rotating cylinder.

Another advantage of this embodiment, when compared with stationarysegmented collector with planar electrodes, is multiple lengths ofordered nanofibres, which enables to produce materials of larger area orvolume with very well ordered internal structure. At very low revs ofthe collector 9 first of all electrostatic forces, which acttransversely between particular electrodes 6 of the collector 9,contribute to the fibre 5 orientation. On the contrary at high revs evenmechanical forces, which capture flying fibre 5 and attract it to theelectrodes 6 of the collector 9 namely in one direction, i.e.perpendicular to the electrodes 6, join the electrostatic forcescontributing to ordered depositing of the fibres 5 onto the collector 9.That way both the important components of forces—electrostatic andmechanical—are added up and thus the resulted degree of uniaxial orderof the fibres 5 is multiplied. This principal is proved by long-termexperimental and theoretically supported results that demonstrateformation of very well oriented fibres 5 of a diameter ranging frommicrofibres to nanofibres with multiply longer length when usingsegmented rotating collector 9, than when using stationary segmentedcollector of similar geometrical parameters. In order that a very goodorientation of fibres 5 may be reached, revolutions of the collector 9described in this patent application are set to a value by several tensof percent lower, than a minimal revolutions of a cylinder with thewhole of conductive surface, namely just because of the contribution ofelectrostatic forces. Reduction of rotating speed leads to steadier airflow, which arises around fast rotating collector 9 and which pullsflying fibres 5 in uncontrolled direction.

Yet another advantage is the possibility of implementation of all theproduction cycle phases in a single closed apparatus, namely in adeposition chamber, where an automatic production without an operatorintervention and without being influenced by external environment isensured, which enables to ensure the process sterility and a highquality of resulting products.

In an advantageous embodiment of this apparatus the rotating collector 9with the set 11 of the electrodes 6 connected to the second potentialcomprises at least three longitudinal electrodes 6, generally Nelectrodes 6, and the accumulator 7 that moves successively alwaysbetween two adjacent electrodes 6 in such a way, that the accumulator 7movement direction is determined by combining a movement in direction ofthe common axis x of rotation of the electrodes 6 of the collector 9,and a movement in direction that forms with the axis x a specified angleβ. The accumulator degree of incline is defined by an angle α. In aplane transverse to the set 11 of the electrodes 6 an angle γ isdefined, which specifies an angular displacement of the accumulator andthe collector 9 to each other. The next collection of the fibres 5 isperformed after turning the electrodes 6 of the collector in relation tothe accumulator through an angle γ=360/N.

In another exemplary embodiment of this apparatus the rotating collector9 with electrodes 6 connected to the second potential includes at leastthree longitudinal electrodes 6, generally N electrodes 6, and theaccumulator 7 that moves successively always between two adjacentelectrodes 6 in such a way, that the next collection of fibres isperformed after turning the electrodes 6 of the collector 9 in relationto the accumulator 7 through an angle γ=90+360/N. However in this casebetween two consecutive collections of the layers 8 of the fibres 5 theaccumulator 7 turns around its axis perpendicular to the surface of theaccumulator 7, which is squared in this case, through an angle of 90°.That way the fibres are deposited in individual layers, where fibres inone layer are perpendicular to fibres of preceding layer.

Yet another exemplary embodiment of the apparatus comprises the rotatingcollector 9 with four longitudinal electrodes 6, and the accumulator 7,which moves in a direction perpendicular to said electrodes 6 axes forenabling of an insertion of inclinable plates of the accumulator 7between said neighbouring electrodes 6 and their release and in thelengthwise direction along the electrodes 6. The accumulator 7 isprovided with four said inclinable plates capturing on their surfacesfibres 5 settled between two closest adjacent electrodes 6. Aftercapturing of fibre layers on said inclinable plates of the accumulator 7said inclinable plates, one after the other, are tilted 180° along theedge of the inclinable plate that is closest to the longitudinal axis ofthe collector 9 and the fibre layer from the inclinable plate iscaptured on the collecting plate that is perpendicular to thelongitudinal axis of the collector 9. Thus after subsequent capturing ofindividual fibre layers from the subsequent inclinable plates four fibrelayers laid on each other are created, the fibres 5 of each layer beingperpendicular to the neighbouring layer.

Very effective drying or solidification of the fibres 5 and effectiveevaporation of a solvent, that is moreover not collected in vicinity ofthe collector 9, are also advantages of the rotating collector 9 withlongitudinal electrodes 6. This has an essential influence on a diameterof the fibres 5 that are formed between electrodes 6 of the collector 9.Their diameter can be reduced by setting the parameters of the process.

In another advantageous embodiment of this apparatus the collector 9 iscomprised of more than three conductive electrodes 6 that are arrangedat regular spacing to each other and at the same from a common rotationaxis x. The accumulator 7 has a shape of a disc and is provided withappropriate notches that enable sliding the accumulator onto thelongitudinal electrodes 6 so that its movement along the rotation axis xand in the vicinity of these electrodes 6 may be enabled. During thismovement, fibres 5, which were deposited in an orderly manner betweenadjacent electrodes 6, are placed spontaneously directly onto a surfaceof the accumulator 7, where stripes of new material are formed, whichstripes are composed of uniaxial ordered fibres 5 with high degree oforientation.

Another advantageous embodiment comprises the cylindrical collector 9composed of at least two longitudinal electrodes 6, generally of totalnumber of N, where N is a natural number, parallelly arrangedelectrodes, the distance of which ranges from 0.1 mm to (π.d/N) mm,where d is double distance of electrodes 6 from the common rotation axisx. In the first limit case very thin conductive wires are used as theelectrodes 6, in the second limit case the electrodes 6 form an integralconductive surface of the cylinder. In the first limit case fibres 5 arecaptured onto the very thin electrodes 6 and resulting material iscomposed of very well ordered fibres 5 only, the fibres having theirdiameter ranging from microfibres to nanofibres. In the second limitcase fibres 5 are wiped off in the same way as above mentioned, whereasduring the fibres 5 depositing a yarn or a filament is formed that iscomposed of multiple fibres 5 with a total length of π.d.

Finally in yet another advantageous embodiment of this apparatus theaccumulator 7 has a shape of a dish for accumulating the collectedlayers 8 of fibres 5. The fibres 5 are compressed into the accumulatingdish by means of a simple piston motion. Individual layers 8 arecompacted in the dish and that way the ordered 3D structure is alsomechanically strengthened. The dish serves for further treatment of theproduct, e.g. by imbedding fibres 5 with another solution, generallywith another medium, a composite material of required properties isproduced.

Hereinafter concrete exemplary embodiments of the apparatus according tothe present invention will by described.

Example 1: Fibrous Layer Composed of Parallel Fibres

Fibres of 16% aqueous solution 1 of polyvinyl alcohol (PVA) wereextruded from a jet emitter 2 through a spinning nozzle 3, and depositedonto a segmented collector 9 (FIG. 2). The electrodes 6 of the collector9 were distant 12 cm vertically from the spinning nozzle 3. Thecollector 9 was provided with four longitudinal electrodes 6 in theshape of thin wires of a circular cross-section with a diameter of 0.8mm. The electrodes 6 distances were 25 mm to each other. By means of alow DC voltage source the collector 9 was set spinning at 2000 revs perminute, which corresponds to the collector linear surface speed of 3.7meter per minute. Another source 4 of high voltage was connected betweenthe spinning nozzle 3 and the collector 9 and its output was set to 28kV. Electrostatic forces gave rise to a formation of a fibre 5 with adiameter ranging from microfibres to nanofibres, which fibre was in turndeposited between the electrodes 6 in the form of a layer 8 of theordered fibres 5. After 30 seconds the fibre 5 depositing wasinterrupted and the rotating collector was stopped or a power supply ofthe collector 9 motor and the high voltage source 4 were switched off.Afterwards the layer 8 of the fibres 5 was wiped off by a slow motionv(t) of the accumulator 7 along the electrodes 6 of the collector 9,whereas the accumulator 7 was inclined at an angle of α=75°. Side viewof this arrangement is depicted in FIG. 3. After the first layer 8 offibres 5 had been deposited onto the accumulator, the collector 9 wasturned through an angle of 90°. At a successive movement of theaccumulator 7 another layer 8 of the fibres 5 was deposited onto itssurface. This process was repeated until all the fibres 5, depositedamong the four longitudinal electrodes 6, were collected (FIG. 4 a).After that the spinning was started again and the whole process wasrepeated. By repeating this process it is possible to produce a layer ofalmost any thickness on the area of (25×25) mm². A surface of such alayer is shown in FIG. 6, which is a photo from electron microscope atmagnification 5000-times. The spinning took place under laboratoryconditions—temperature 24° C. and relative humidity 40%.

Example 2: Material with Regular 3D Structure Composed of FibresPerpendicular to Each Other

Fibres 5 of a diameter ranging from microfibres to nanofibres weredeposited onto the rotating collector 9 with four longitudinalelectrodes in the same way as mentioned in example 1. After stopping thespinning process and the rotating collector 9, the fibres 5 were wipedoff by the accumulator 7 (FIG. 5 a). The accumulator 7 was in motionalong the conductive rodlike electrodes 6 of the collector 9 so that thefirst layer of the fibres 5 was formed on a surface of the accumulator7. Afterwards the whole collector 9 turned through an angle of 90° andsimultaneously also the squared accumulator 7 sized 25×25 mm turnedthrough an angle of 90°. The accumulator 7 was set in motion along theconductive rodlike electrodes 6 of the collector 9, during which timethe second layer of fibres 5 was being deposited. The fibres 5 in thesecond layer 8 were deposited perpendicularly to the fibres 5 of thefirst or the preceding layer 8. This process was repeated four timesuntil all the fibres 5 were wiped off the collector 9. Thereafter thecollector 9 was set spinning and the spinning process was started. Thesample produced by this process has a regular 3D structure of an area of(25×25) mm². An example of such material surface is shown in FIG. 7,which is a photo from electron microscope at magnification 1000-times.

INDUSTRIAL APPLICABILITY

The present invention can be used for production of materials that areareal (2D) or voluminous (3D) from the macroscopic point of view, andwhich are composed of nanofibres or microfibres, whereas the internalfibrous structure of these materials is regular, ordered in onedirection or in more directions.

1. A method of production of two-dimensional or three-dimensionalfibrous materials of fibres of a diameter ranging from microfibres tonanofibres, where in step a) the fibre is continuously drawn out of asolution, and pulled to a rotary set of n electrodes, where n is anatural number, by means of an electrostatic field, the individualelectrodes of the set being arranged at regular spacing to each otherand at the same distance from the set of electrodes rotation axis andparallel with it, the fibre being wound on the set of the electrodes byrotating the set of the electrodes, after which in step b) theelectrostatic field is disconnected and rotation of the set of theelectrodes is stopped, and a layer of the fibres formed in the fieldbetween two adjacent electrodes is removed by an accumulator, and in thesubsequent step c) the rotating set of the electrodes turns through anangle of 360/n, the layer of the fibres, formed between two adjacentelectrodes in the field adjacent to the field from which the layer wasremoved in preceding step b), is removed by the accumulator andsuperimposed on the layer removed in step b), and this step is repeatedin total n-times.
 2. The method of claim 1 wherein before the step c),where the layer formed in the field between two adjacent electrodes isremoved, the accumulator turns round slightly such that the layerremoved in step c) has a fibre direction different from a fibredirection of the preceding layer.
 3. The method of claim 1 wherein thesuperimposed layers of the fibres are pressed together.
 4. The method ofclaim 3 wherein a required spatial shape of a final product is formed bycompressing the layers of the fibres.
 5. The method of claim 4 whereinthe shaped compressed layers are imbedded with a medium, thus creating acomposite material of required properties.
 6. An apparatus for theproduction of two-dimensional or three-dimensional fibrous materials ofthe fibres for implementing the method of claim 1, comprising at leastone spinning nozzle connected to a first potential, and the set ofelectrodes is attached to a second potential, and the accumulator forcollecting fibres is settled between two adjacent electrodes, whereinthe set of the electrodes is rotatable about a rotation axis, andindividual electrodes of the set are arranged at regular spacing to eachother and at the same distance from the rotation axis and eachindividual electrode extends along a longitudinal axis parallel with therotation axis, and the accumulator is, in relation to the electrodes,arranged movably in the direction of the longitudinal axes of theelectrodes for collecting the fibres settled between two adjacentelectrodes, and is, in relation to the electrodes, arranged movably inthe direction perpendicular to the longitudinal axes of the electrodesfor it being brought into engagement to collect fibres settled betweentwo adjacent electrodes, and being brought out of engagement afterfinishing the collection of fibres settled between two adjacentelectrodes.
 7. The apparatus of claim 6 wherein individual electrodeshave an electrode surface and the accumulator has a shape of aparallelogram, the width of which is smaller than a distance between thenearest surfaces of a adjacent electrodes to enable its insertionbetween said adjacent electrodes.
 8. The apparatus of claim 7 whereinthe accumulator is arranged rotationally around a line perpendicular toa surface of the accumulator and passing through a centre of theaccumulator surface for depositing the subsequent layer of the fibressettled between two adjacent electrodes with the fibre directiondifferent from the direction of the fibres of the preceding layer. 9.The apparatus of claim 7 wherein individual electrodes have an electrodesurface and the accumulator has a squared shape with its side shorterthan a distance between the nearest surfaces of two adjacent electrodes,and is arranged rotationally around a line perpendicular to a surface ofthe accumulator and passing through a centre of the accumulator surfacefor turning the accumulator through an angle of 90° for depositing thesubsequent layer of the fibres settled between two adjacent electrodeswith the fibres direction perpendicular to the direction of the fibresof the preceding layer.
 10. The apparatus of claim 6 wherein theaccumulator has a shape of a dish for depositing the collected layers ofthe fibres, the apparatus being further provided with a piston forpressing the fibres into the accumulator and for compressing theindividual layers of the collected layers of the fibres for the purposeof mechanical strengthening of an ordered three-dimensional structure.11. The apparatus of claim 10 wherein the accumulator is arrangedrotationally around a line perpendicular to a surface of the accumulatorand passing through a centre of the accumulator surface for turning theaccumulator around slightly for depositing the subsequent layer of thefibres settled between two adjacent electrodes with the fibres directiondifferent from the direction of the fibres of the preceding layer. 12.An apparatus for the production of two-dimensional or three-dimensionalfibrous materials of fibres of a diameter ranging from microfibers tonanofibres, comprising: at least one spinning nozzle configured toproduce fibres, a rotating collector configured to collect fibres fromthe at least one spinning nozzle, the rotating collector including a setof n electrodes rotatable about a rotation axis, where n is a naturalnumber, the individual electrodes being arranged at regular spacing toeach other and at the same distance from the rotation axis and eachindividual electrode extending along a longitudinal axis parallel withthe rotation axis, the set being configured such that the fibres arewound on the set of electrodes when the set is rotated, a first electricpotential and a second electric potential, the at least one spinningnozzle being connected to the first potential and the set of electrodesbeing connected to the second potential, and an accumulator disposedbetween two adjacent electrodes and being moveable in the direction ofthe longitudinal axes of the individual electrodes for collecting thefibres settled between the two adjacent electrodes, the accumulatorbeing further moveable in a direction perpendicular to the longitudinalaxes of the individual electrodes for moving into engagement to collectfibres settled between the two adjacent electrodes and out of engagementafter finishing the collection of fibres settled between the twoadjacent electrodes.